Merge pull request #5268 from mysterywolf/SYSCALL

[libc]重新梳理read write桩函数实现

1 files changed, 25 insertions, 16 deletions

diff --git a/components/libc/compilers/dlib/syscall_write.c b/components/libc/compilers/dlib/syscall_write.c
index 72bac6ba49..9a7707e9d3 100644
--- a/components/libc/compilers/dlib/syscall_write.c
+++ b/components/libc/compilers/dlib/syscall_write.c
@@ -9,7 +9,7 @@
  */
 
 #include <rtthread.h>
-#include <yfuns.h>
+#include <LowLevelIOInterface.h>
 #include <unistd.h>
 #ifdef RT_USING_POSIX_STDIO
 #include "libc.h"
@@ -19,6 +19,20 @@
 #define DBG_LVL    DBG_INFO
 #include <rtdbg.h>
 
+/*
+ * The "__write" function should output "size" number of bytes from
+ * "buffer" in some application-specific way.  It should return the
+ * number of characters written, or _LLIO_ERROR on failure.
+ *
+ * If "buffer" is zero then __write should perform flushing of
+ * internal buffers, if any.  In this case "handle" can be -1 to
+ * indicate that all handles should be flushed.
+ *
+ * The template implementation below assumes that the application
+ * provides the function "MyLowLevelPutchar".  It should return the
+ * character written, or -1 on failure.
+ */
+
 #pragma module_name = "?__write"
 
 size_t __write(int handle, const unsigned char *buf, size_t len)
@@ -29,36 +43,31 @@ size_t __write(int handle, const unsigned char *buf, size_t len)
 
     if ((handle == _LLIO_STDOUT) || (handle == _LLIO_STDERR))
     {
-#ifdef RT_USING_POSIX_STDIO
-        if (libc_stdio_get_console() < 0)
-        {
-            LOG_W("Do not invoke standard output before initializing libc");
-            return 0;
-        }
-        return write(STDOUT_FILENO, (void*)buf, len);
-#elif defined(RT_USING_CONSOLE)
+#ifdef RT_USING_CONSOLE
         rt_device_t console_device;
 
         console_device = rt_console_get_device();
-        if (console_device != 0)
+        if (console_device)
         {
             rt_device_write(console_device, 0, buf, len);
         }
 
-        return len;
+        return len; /* return the length of the data written */
 #else
         return _LLIO_ERROR;
-#endif /* RT_USING_POSIX */
+#endif /* RT_USING_CONSOLE */
     }
     else if (handle == _LLIO_STDIN)
     {
         return _LLIO_ERROR;
     }
-
+    else
+    {
 #ifdef RT_USING_POSIX
-    size = write(handle, buf, len);
-    return size;
+        size = write(handle, buf, len);
+        return size; /* return the length of the data written */
 #else
-    return _LLIO_ERROR;
+        return _LLIO_ERROR;
 #endif /* RT_USING_POSIX */
+    }
 }